The broad objective of this project is to understand the biology of the glycoprotein hormones thyrotropin, luteinizing hormone, follicle stimulating hormone, and chorionic gonadotropin. Studies of the human pituitary response to thyrotropin releasing hormone indicate specificity of its pharmacologic effects and suggest that biologically ineffective immunoreactive forms of thyrotopin may be secreted by normal pituitary tissue. Studies of structure-function relationships indicate that human chorionic gonadotropin has intrinsic follicle stimulating activity and thyroid stimulating activity. Future directions of the project include development of more sensitive methods for measurement of glycoprotein hormones, investigation of potential heterogeneity of pituitary secretory products, and delineation of the primary and secondary biologic functions of the glycoprotein hormones. BIBLIOGRAPHIC REFERENCES: Nisula, B.C., G. Claubiger, J.P. Louvet, and T.N. Chase: Effect of a Large Dose of Thyrotropin Releasing Factor on Pituitary and Thyroid Function in Patients with Parkinsonism. Clinical Endocrinology 5:561, 1976. Louvet, J.P., S.M. Harmon, B.C. Nisula, G.T. Ross, S. Birken, and R. Canfield: Follicle Stimulating Activity of Human Chorionic Gonadotropin. Endocrinology 99:1126, 1976.